Heretofore, natural proteins such as gelatin, casein, egg albumen, and glue, mixed with a bichromate salt have been used as water-soluble photosensitive resins. However, these natural proteins have problems in that it is difficult to obtain resins of consistently stable quality, and the use of the bichromate salt may cause a pollution problem. Furthermore, photosensitive resins comprising these natural proteins and the bichromate salt are inferior in storage stability and undergo a dark reaction.
As photosensitive agents that eliminate such problems, photosensitive poly(vinyl alcohols) which have a pendant styrylpyridinium or styrylquinolinium photosensitive group have been proposed (Japanese Patent Publication No.56-5761/1981, Japanese Patent Publication No.56-5762/1981, Japanese Patent Publication No.56-11906/1981). These photosensitive poly(vinyl alcohols), which have good storage stability and high sensitivity, have been said to be suitable as photosensitive resins for use in screen printing (Japanese Patent Publication No.56-40814/1981), lithographic and relief printing (Japanese Patent Publication Laid-open No.62-25750/1987), press correction (Japanese Patent Publication Laid-open No.61-186954/1986, Japanese Patent Publication Laid-open No.61-186955/1986), photosensitive films (Japanese patent publication Laid-open No.55-135834/1980, Japanese patent Publication Laid-open No.61-175639/1986), production of color filters (Japanese Patent Publication Laid-open No.59-2039/1984, Japanese Patent Publication Laid-open No.60-129738/1985, Japanese Patent publication Laid-open No.60-129742/1985), production of cathode ray tube phosphor faces (Japanese Patent Publication Laid-oPen No.56-147804/1981, Japanese Patent Publication Laid-open No.58-164677/1983, Japanese Patent Publication Laid-open No.59-11388/1984), binders or overcoating layers for thermal recording materials (Japanese Patent Publication Laid-open No.62- 257881/1987, Japanese Patent Publication Laid-open No.62-257882/1987), starching agents for textiles (Japanese Patent Publication Laid-open No.57-133276/1982), or immobilization of biocatalysts (Japanese Patent Publication No.56-54155/1981, Japanese Patent Publication No.58-30035/1983, Japanese Patent Publication Laid-open No.58-129976/1983).
However, the above prior art photosensitive poly(vinyl alcohols) have been defective, among others, in that they tend to undergo coloring when heated, and thus have been insufficient for use in the above applications. Especially for the production of color filters, the resins themselves undergo coloring due to heat applied in hardening of protective films, heat treatment of oriented films or sealants, or deposition of transparent electrodes, thus considerably deteriorating the spectral characteristics of the color filters.